I was wondering if there was any type of diagram out there for what resolution you need for 4X6 printing vs. 5X7 vs. 8X10...etc. I am resizing and saving all of my images and I need to know what the smallest image I should keep in case I want to print 4X6 in the future. I keep all of my RAW files backed up elsewhere for when I want larger prints.
Sounds like you should keep 300 dpi 4x6's saved to keep it simple. If you are proccessing the RAWs and retouching the photographs, you may want to save 300 dpi 8x10s of those. You can always downsize the 8x10s. If you save the image in a smart object layer at your largest size, (file size will be bigger) you will be able to go back and forth non-destructivly between sizes with one file.